The amount reported with code AA in box 12 of your W-2 is not a Roth IRA contribution. It is a contribution to a Designated Roth Account in your 401(k).
None of this is deductible on your tax return. Your employer has already excluded your elective deferrals to the traditional 401(k) account, shown with code D in box 12 of your W-2, from the amount reported in box 1 of your W-2 as taxable income. Contributions to the Roth account in your 401(k) are not excludible from income. Contributions to a Roth IRA are not deductible.
Depending on your AGI, you might qualify for a Retirement Savings Contributions Credit based on these contributions and other factors. Under Deductions & Credits, be sure to enter only your personal Roth IRA contribution.
